What are the effects of being in space too long?

Many people show symptoms of "space sickness," such as headaches, nausea, and vomiting. In the low gravity of space, the information received from the vestibular organs changes. This is thought to confuse the brain, leading to space sickness. But this condition does not continue for very long. If you stay for a few days in space, your brain adjusts its interpretation of the vestibular information, so the space sickness goes away. When you return to earth, you experience the effects of earth's gravity again, and thus "gravity sickness" sometimes occurs, with similar symptoms as space sickness. If you stay for a while in space, the fluids in your body balance out, and facial swelling typically begins to disappear after a few weeks. Conversely, astronauts returning to earth often experience dizziness when standing up, known as orthostatic hypotension. This occurs because gravity on the earth is stronger than in space, and it is more difficult to deliver blood from the heart to the head. In space, blood can be delivered with less force, so weakening of the heart muscles may also be a cause of dizziness when standing. If you stay for a long time in space, your muscles and bones will weaken, primarily in the legs and lower back. Muscles weaken and bone mass decreases if you stay for a long time in space. In outer space, with no atmosphere, radiation is more intense and has major impacts on the human body. If a person is exposed to a lot of higher energy radiation, the risk increases that they will develop diseases such as cancer. Astronauts develop stress before even realizing it when living and working together in a cramped space with other astronauts for a few months. The astronauts on the ISS come from different places, including Russia, America, Canada, Europe, and Japan, so factors such as language barriers and cultural differences may also lead to stress.

Spending months in microgravity is brutal on the body. Without the Earth’s gravitational pull, muscles shrink, bones weaken and bodily fluids shift. Astronauts lose muscle mass rapidly because they do not use their legs to support their weight. Their bones become fragile and they lose 1 percent of their bone mass per month – equivalent to an entire year of ageing on Earth. Radiation is another major concern. Although the ISS is shielded by Earth’s magnetosphere, astronauts on missions lasting six months or longer receive more than 10 times the radiation than what is naturally occurring on Earth. Prolonged exposure is linked to higher cancer risks and potential cognitive decline. Body mass and fluids: Astronauts lose about 20 percent of their body fluids and about 5 percent of their body mass while in space. Returning to Earth does not immediately undo months of strain on astronauts’ bodies. As their bodies readjust to gravity, they experience balance issues, dizziness and weakened cardiovascular function. Even months after landing, not everything recovers. They face long-term health risks, including cancer, nerve damage and degenerative diseases. Six months later: The risk of bone fractures remains as well as an increased risk of cancer. Psychosomatics and cognition: Radiation may cause brain damage and the onset of Alzheimer’s disease. Immune system: The immune system weakens. Radiation exposure from six months in space equates to 10 times the annual exposure on Earth.

These hazards do not stand alone. They can feed off one another and exacerbate effects on the human body, which are being studied using ground-based analogs, laboratories, and the International Space Station. Through meticulous research, NASA is gaining valuable insight into how the human body and mind might respond during extended forays into space. On Mars, astronauts would need to live and work in three-eighths of Earth’s gravitational pull for up to two years. Throughout this time, their bodies – muscles, bones, inner ear, and organs – will be adjusting to new gravitational loads. Behavioral responses occur among groups of people isolated and confined in a small space over a long period of time. Crews must be carefully chosen, trained, and supported to ensure they can work effectively as a team for months or years in space. Mars is, on average, 140 million miles from Earth. Rather than a three-day lunar trip, astronauts would be leaving our planet for roughly three years. Planning and self-sufficiency will be key to successful deep space missions.